1. Technical Field of the Invention
The present invention relates to an electronic musical keyboard instrument, and more particularly, to a keyboard device for an electronic musical keyboard instrument that is capable of being manufactured compactly with an improved arrangement of a key supporting part.
2. Description of the Related Art
A typically known electronic musical keyboard instrument, such as a portable keyboard, a synthesizer, an electronic organ, an electronic piano, etc., has a keyboard structure which is configured such that plural keys constitute a key array unit and plural key array units are united and fixed to a key frame. For example, reference is made to FIGS. 2 and 3 of Patent Reference 1 (Japanese Patent Registration No. 2628566).
For example, keys of one octave are separated into one structure which includes plural black keys (a black key array unit) and plural structures in which white keys are arranged in a comb teeth shape while being separated from each other by an interval of at least one key (for example, a white key array unit including four keys of C, E, G and B, and a white key array unit including three keys of D, F and A). Rear end portions of the respective keys are coupled to a common base part and integrally formed by resin, and the plural key array units are united at the common base part and fixed to a key frame.
FIG. 7 is a view illustrating a key to explain the drawback of a conventional key array unit.
In the drawing, a reference numeral 81 refers to a key body, 81a refers to a horizontal hinge section which allows the key body 81 to pivot in a stroking direction of the key by elastic deformation of a rear end portion of the horizontal hinge section, 81b refers to an orthogonal hinge section which is orthogonal to the horizontal hinge section 81a and which allows the key body 81 to move in a transverse direction of the key, and 82 refers to a band-shaped common base part.
The horizontal hinge section 81a is configured as a horizontal thin plate piece which has a thin thickness along a downward direction of the key (a vertical direction of the key) and is disposed along a longitudinal direction of the key (a direction from a front end of the key to a rear end of the key). The orthogonal hinge section 81b is configured as an orthogonal thin plate piece which has a thin thickness in the transverse direction of the key (a widthwise direction of the key) and is disposed along the longitudinal direction of the key.
The horizontal hinge section 81a is connected to the orthogonal hinge section 81b by a coupling part 81c therebetween, and the orthogonal hinge section 81b is connected to the common base part 82 by a coupling part 81d therebetween. Each of the coupling parts 81c and 81d is formed in a plate piece shape which has a predetermined thickness along the longitudinal direction of the key and is disposed along the width direction of the key.
A reference numeral 81e refers to a stopper piece, which contacts a stopper provided at the key frame to restrict a pivot range of the key body 81. In Patent Reference 1 (see FIG. 1), the stopper piece 81e is inserted into a slit formed at the frame, to also function as a key guide.
Although the key body 81 is deformed in the width direction of the key due to after-shrinkage or the like during fabrication of the key array unit, the orthogonal hinge section 81b is bent slightly so that the key body 81 moves in the width direction of the key to adjust its position, and an inclination in the width direction of each key is adjusted so that the key body 81 is at right angle to the common base part 82.
However, because the key body 81 is connected to the common base part 82, which is disposed along the longitudinal direction, at the rear end portion while interposing a key supporting part having the horizontal hinge section 81a, which is disposed along the longitudinal direction, between the key body 81 and the common base part 82, a length between a front end and a rear end of the keyboard device is lengthened. Accordingly, a length between a front end and a rear end of an electronic musical keyboard instrument accommodating the keyboard device is also lengthened. Further, the upper portion of the common base part 82 is covered with a panel of a main body of an instrument, and a space for mounting switches and the like below the panel is required. Accordingly, there is a drawback that the panel of the main body of the instrument should be located sufficiently high over the common base part 82.
In order to shorten the length between the front end and the rear end of the keyboard device, the orthogonal hinge section 81b is possibly removed, but the horizontal hinge section 81a and the common base part 82 should not be removed.
Meanwhile, a keyboard device which uses a vertical hinge as the key supporting part is known. For example, reference is mad to Patent Reference 2 (Japanese Utility Model Laid-Open Publication No. H6-31507).
A vertical hinge section is formed at a middle portion in the longitudinal direction of each key constituting the key array unit (a position where the rear face portion of the black key is located). The vertical hinge section is configured as a thin plate piece which has a thin thickness in the longitudinal direction of the key, is disposed along the width direction of the key, and extends downward in the vertical direction of the key. The vertical hinge section allows the front end portion of the key to pivot in the stroking direction of the key. The vertical hinge section is integrally formed with the band-shaped common base part which is positioned on the same plane as the vertical hinge section. In this Patent Reference, a balance weight is provided at the rear portion of the key, or the rear end portion of the key is in contact with a lever to which the balance weight is attached, and thus the key body is configured to extend rearward from the position where the rear face portion of the black key is located.
If not extending the rear end portion of each key rearward but extending downward and making the extended portion function as the vertical hinge section, the keyboard device can be shortened in the longitudinal direction of the key when compared to the horizontal hinge section.
At this time, if extending the vertical hinge section downward sufficiently long, because the hinge is displaced while twisting by force exerted in the width direction of the key, the movable range becomes broad.
As described above, if using the aforesaid vertical hinge section as the key supporting part, extending the rear end portion of each key in a perpendicular direction, forming the extended portion to have a thin thickness to function as an elastic deformation part, and connecting the lower end of the elastic deformation part of each key to the band-shaped common base part, the length between the front end and the rear end can be shortened in comparison to the horizontal hinge section.
However, the rear portion of the key body is blocked by the vertical hinge section. As a result, an empty space is formed below the rear portion of the key body. On occasion, other components of the electronic musical keyboard instrument are mounted in the empty space.
For example, there is another known keyboard device that is capable of guiding a player to press down the proper keys during the musical performance. This conventional keyboard device is constituted such that a light emitting diode for guiding the musical performance is mounted under the front portion of each key body, i.e., the key pressing position, and a light guide member is mounted to the back face of the key to guide the light to the rear portion of the key. For example, reference is made to Patent Reference 3 (Japanese Patent Laid-open Publication No. 2001-265348).
However, because the front lower portion of the key body is hidden by the player's finger and palm during the musical performance, the player cannot occasionally see the musical performance guide member. Therefore, it is effective to guide the light to be irradiated to the rear portion of each key, but the light guide member causes increase in costs.
There is another type of keyboard product which is constituted such that a light emitting diode is mounted to a position corresponding to each key on a front end of a panel covering the rearward of the key board in order to guide the musical performance. However, because the key itself does not glow, the player has difficulty in distinguishing the keys to be pressed down. Further, because the panel is opaque, there are drawbacks of necessarily forming holes to guide light at the panel and attaching a light-permeable sheet to the surface of the panel.
To cope with the above problems, it can be considered to dispose the light emitting part below the rear portion of each key body. However, it is impossible to use the aforesaid empty space because of the presence of the aforesaid vertical hinge section.